RCD for electric shower

[Trinity36]

Does a shower circuit have to have its own RCD, if there is already one in the consumer unit? My existing shower is supplied via a MEM consumer unit which has a 30mA RCD (marked ELCB) but I am being told I now need another RCD on the shower circuit (I am rewiring for a more powerful shower). Is this necessary? I would have thought the integral RCD would suffice.

Any advice welcome. I of course want to be safe but I also don't want unnecessary expense.

I live in Edinburgh so it may be a Scottish regs thing.

 

[JohnD]

press the test swich on the rcd and see if it cuts power to the shower. with a split-load C/U it may not, so would need an RCBO or something for the shower circuit. This is easy to fit on modern MEM but might cost £30 or so foir the part.

post a pic of the CU and cables around it if you can.
//www.diynot.com/forums/viewtopic.php?t=129539
Otherwise tell us any part nos or product names you can see, including on the RCD and MCBs

Certain old ELCBs are unsafe and need replacing.

 

[holmslaw]

..

 

[ericmark]

An Earth Leakage Circuit Breaker as “holmslaw” says includes voltage types but since you say 30ma this is not the case with yours.
The regulations refer to selectivity between RCD’s and the only place where you are required to use two RCD’s both of same type and rating to protect the same circuit is the supply to a caravan where both the caravan site has one and the caravan has one. Both being 30ma and having a 40ms max trip time.
The comments on current rating are of course valid but that did not seem to be your question.